1. Field of the Invention
This invention relates to a process of dissociating a culture of mycobacteria on liquid media. More particularly, the present invention relates to the production of phenotypes of mycobacteria, at least two of which have been found to possess interesting biological activities.
2. Description of the Prior Art
As early as 1927, Petroff (Microbic dissociation: the tubercle bacillus Proc. Soc. Exp. Biol. Med., 24: 632-634) has shown that several types of tubercle bacilli dissociated into 2 distinct variants when cultured on the solid gentian-violet-egg medium: the so-called rough and smooth colonies. In subsequent years, and more recently, the dissociation phenomenon of mycobacteria has been confirmed repeatedly. With the advent of transparent solid media, the previous classification into rough and smooth variants was further subdivided into Rough C, R, F, etc, and Smooth S, D, T, etc, based on the microscopic characteristics of colonies. Some of these colonial forms appear to be specific for a given species of tubercle bacilli and of atypical mycobacteria; they can thus be of value in early identification. Other investigators working mainly with BCG substrains, have described the spreading, intermediate and nonspreading types of colonies.
Investigations have so far shown that there is no conclusive proof that the different colonial forms represent true mutations of mycobacteria. However, many factors such as the composition of solid media, cultural conditions, etc., can influence colony morphology. Thus, it would appear that the dissociation phenomenon represents changes in the phenotype of mycobacteria.
Early investigations had shown that differences in the protein, glycogen, carbohydrate, and lipid contents exist between the rough and smooth variants of a few strains of mammalian tubercle bacilli. However, the relationship between these constituents and the colonial forms is still not well defined. More recently, Fregnan et al. have reported a good correlation between the mycoside content and the colony morphology of atypical mycobacteria.
It is an object of the present invention to provide a process whereby mycobacteria are dissociated into phenotypes.
It is another object of the present invention to provide conditions under which mycobacteria are cultured to produce phenotypes thereof.